The proposed project will prospectively investigate physical and social environmental exposures as determinants of Health-Related Quality of Life (HRQOL) in adult asthma and rhinitis, focusing on the role of severity of disease as a principal mediator between the physical and social environment and HRQOL. The proposed study, a competitive renewal of an R01 near completion, builds upon our current research elucidating multifactorial models of physical and social environmental risks. The specific study aims are: 1.] Delineate the specific pathways linking physical and social environmental exposures to disease-specific and general HRQOL in adult asthma and rhinitis, including mediation by changing disease status overtime;2.] Identify specific risk factors, such as personal socioeconomic status, that modify the impact of these environmental factors on disease severity or the effect of severity on HRQOL in adult asthma and rhinitis. To accomplish these goals, we will assemble a prospective cohort of 636 adults, merging our ongoing asthma-rhinitis cohort (the basis of the current R01) with a second cohort of adults with severe asthma established as part of a methodologically similar study. Subjects will undergo 3 waves of structured telephone interviews over the study period to ascertain environmental exposures, disease severity, and HRQOL. Two home visits will be conducted in a subset of subjects (n=380) to assess the home environment (including measurements of dust antigen, airborne particulate, and dampness), measure pulmonary function and exhaled fraction of nitric oxide, and collect biological samples to measure secondhand smoke exposure. We will also carry out geocoding for linkage to external data sets for U.S. Census information, traffic density, and levels of ambient air pollutants. We will test predictive models of physical and social environmental factors, including measures of indoor air quality, ambient pollution, and neighborhood and community status, estimating the longitudinal effect of these factors on HRQOL. We will assess the role of disease severity as a mediating factor in the causal pathway leading from environmental exposures to changes in HRQOL;we will also assess selected individual factors that may be effect modifiers of this relationship, especially personal socioeconomic status (SES). Public Health Importance: In order to understand the complex web of factors influencing airway disease outcomes from the perspective of persons with disease, there is a critical need for an analytic approach that can test the effect of multiple combined environmental risk factors on HRQOL, assess the mediating role of disease severity, and take into account individual effect modifiers. The long- term goal of our study is to identify modifiable factors and subgroups at high risk in order to improve HRQOL among adults with asthma. The proposed project builds upon our success in the current R01 by testing more specific pathways in the context of our accumulated experience to date.